Graffiti, namely writing or drawing on walls or other objects, often in public areas or being exposed to the public eye, is a well known way of artistic expression. Graffiti is used for esthetical decoration of walls, fences, street objects such as garbage or recycling containers etc., or as means for publically—but often unanimously—protesting or expressing social, economical or other political views.
Graffiti is often performed by a lone performer with relatively simple tools. For example, a single spray-can may be all that is used to generate a complete graffiti artwork. As a result, when employed to walls, graffiti is often restricted to low-to-moderate heights, usually comparable to a man's height or such that may be reached with a simple ladder. Employing graffiti to walls at heights of more than a few meters above ground might either involve a considerable risk of fall injuries for the performer in case of an accident, or might require complex and fairly expensive equipment—such as a lift—and might further require complex coordination e.g. with municipal authorities, to enable the work using the public domain.
U.S. Pat. No. 6,419,190 discloses an airborne cleaning and painting robot having the capability to fly, and a cleaning or painting mechanism that can be located at various positions on the robot body. The robot comprises of a flying unit connected with a feeding tube to a ground-moving base that holds the pressurized cleaning solution or paint. A steering mechanism in contact with the surface being cleaned or painted for changing the direction of advance of the flying unit while a back propeller or main rotors push the flying body against the working surface. An array of sensors is mounted of the flying unit body to get the physical size of the working surface, avoid obstacles, maintain stability and control other critical characteristics.
Korean patent KR 1128526 discloses a cleaning robot for windows of a high-rise building, using propellers to increase the adhesion pressure onto window surface. The window cleaning robot has cleaning equipment arranged in space part of main body, and thrusting apparatus adhering two pairs of driving wheel, where cleaning surface is formed in both sides of main body.
Chinese patent CN101317744 discloses a wall surface cleaning robot based on the positive/negative pressure adsorption principle. A cleaning mechanism and a water inlet and outlet mechanism of the invention are installed in a shell body. A wheel type traveling system is installed at the lower part of the shell body. A three phase motor is installed on the upper end face of the shell body, equipped with a propeller and a centrifugal fan. A dry brush, a wet brush, a suction roll and a squeeze roll are installed in the shell body in sequence from front to rear.